Sapphire

Some of this data came from Ferroceramic.com, some came from an old MIC Technology databook. Sapphire formula is Al₂O₃, exactly the same as pure alumina. Sapphire is crystalline while alumina is amorphous. Thanks to Luciano, for pointing out the composition!

Formula or Composition:	Al2O3
Dielectric Constant ():	9.3 - 11.5
Dissipation Factor (a.k.a. loss tangent, or tan):	0.00002
Temperature Coefficient of :	ppm/°C
Bulk Resistivity:	10E17 -cm
Temperature Coefficient of Resistivity (TCR):	ppm/°C
Mass Density:	3.97 gr/cc
Specific Heat:	J/g/°C
Thermal Conductivity (k):	40 W/m°C
Temperature Coefficient of Expansion (TCE):	0.6
Melting Point, °C:
Melting Point, °F: